Hi Peggy! We get this question frequently, and although it seems like a great idea, I'm sorry to say that you can't use a multi-day base ticket to visit different Disney parks on the same day. To enter more than one of the theme parks on the same day, you'll need to
have the Park Hopper option on your multi-day base ticket. Without the Park Hopper, if you attempted to
use your base ticket at a second park on the same day, the system would reject
it, rather than taking an additional day off. Your base ticket will allow you
to go in and out of the same park each day, but it won't allow you to visit
multiple parks.
I always add the Park Hopper option to my tickets, but like you, I don't always use it. I'm budget-minded, and I like to find ways to save money on my Disney vacations, but in my opinion, the Park Hopper option is worth the cost. I like to avoid long lines at the attractions, and
when the park I'm visiting becomes crowded, I like being able to hop to a park
with lower attendance. I don't always need to do that, but having the Park Hopper prevents me from getting stuck in an overly-crowded park. To me, that flexibility and the ability to avoid lines is
priceless.
Hope you have a wonderful time in March! Come visit us again at the Moms Panel if you have more questions!